Phys Ed: Can Running Actually Help Your Knees?

Will decades of running wear out my joints, and leave me with arthritis? 

It's a common question among runners, and the body of research seems to be saying no.  In fact, runners knees may be better off than the average nonrunner.  But be careful if you've already had an inury.

http://well.blogs.nytimes.com/2009/08/11/phys-ed-can-running-actually-help-your-knees/